Composite layer films for color photography and the processing thereof



Dec. 20, 1938. H. D. MURRAY ET AL 2,140,847

COMPOSITE LAYER FILMS FOR COLOR PHOTOGRAPHY AND THE PROCESSING THEREOF Filed June 21, 1935 EMULSION\ EMULSION- IIEMULSION FILM Fl LM"" ZZEM U LSION *VARNISH LAYER ML I LLLL MP0 MEN 7' OUTER EMULSION Qf-oursnz EMULSION LLLLL \SUPPORT [/1 uem orsx Patented Dec. 20,1938

UNITED STATES PATENT j OFFICE COMPOSITE LAYER. FILMS Fon oorlonrnorocmrnr AND THE PROCESSING,

'rnnnnor v Application June 21, 1935, Serial No. 27,804 In Great Britain June r25, 193 4 This invention consists in improvements in or relating to composite layer films for use incolor photography. In one type of process which has been proposed for producing a colored photo graphic image the sensitive emulsion contains in addition .to the silver halide a color-forming substance which on development and bleaching of the silver image forms an image in color. It is also well known in another type of process to prepare colored images by treatment of a silver image by chemical toning, or by dye toning, or by for example the methods described in British Specifications Nos. 377,706 and 363,616.

It is an object of the present invention to provide a new material and method of processing this material which combines the above two types of processes for producing colored images in advantageous form in the production of a threecolor photographic record.

The invention provides light sensitive multilayer photographic material for use in the production of colored photographic records and comprising three (or four) layers of light sensitive emulsion of which the outer layers are normal photographic emulsions and the intermediate layers (or at least one of the intermediate layers where there are two), is sensitive to a diiierent portion of the spectrum from that to which at least one of the outer two layers is sensitive and contains in addition to the light sensitive salt a color-forming substance of the kind which reacts with the lay-products of development to produce an image and is so selected that the intermediate layer (or layers) provides an image in one of the three subtractive colors.

In this specification the term normal photo-' graphic emulsion is intended to refer to sensitive emulsions which contain no colored substance or color-forming substance other than the normal sensitizing dyes which may be included during manufacture and removed from the emulsion in the processes of development and fixing.

In one form of the invention the photographic material comprises a transparent support and on one side of the support two layers of sensitive emulsion and on the other side one layer of sensitive emulsion, the inner of the two layers on the one side of the support containing the color-forming substance.

In a preferred form of the invention the colorforming substance is one capable of reacting with a photographic developer to give a colored deposit which remains in situ when the photographic silver image is bleached.

The invention includes the method of producing a. colored photographic record which comprises the steps of printing from a set of three color separation records onto light sensitive photographic material as described above while employing means to ensure that the outer layers and the inner layer (or when two inner layers are used at least one inner layer) are each exposed efiectively only to a difierent color separation record, developing and bleaching the images, thereby producing a colored image in the intermediate layer or layers and then color toning or coloring the two outer layers to the other two subtractive colors respectively.

The accompanying drawing illustrates several embodimentsoi the film of the invention.

In one method of carrying the invention into effect, film material as shown in Figure 1 of the drawing and having two outer layers and one intermediate layer of emulsion is used. The two outer layers are sensitive to substantially the same portion of the spectrum and the intermediate layer is sensitive to a difierent portion of the spectrum. The intermediate layer is printed from one part separation negative utilizing light of color to which the two outer layers are insensitive but to which the intermediate layer is sensitive. The latent image of this negative is therefore formed only on the intermediate layer. The two outer layers are then printed from the two remaining part separation negatives utilizing light to which the two outer layers are sensitive and the intermediate layer is insensitive. In order to ensure that the light employed for printing one of the outer layers shall not affect the other outer layer, a filter is provided between these two layers either by dyeing the intermediate layer or the support or by providing a separate dyed layer. After printing the whole composite film is developed and the colored image in the intermediate layer is produced in the following manner. The emulsion employed is of the highest possible contrast and incorporates a leuco dye or other compound which develops color where a silver image is developed. Suitable compounds are the esters of leuco vat dyes or substances such as those described in British Specification No. 376,794. In this case the emulsion is impregnated by passing it through a bath containing 2.5% of alpha-naphthol dissolved in alcohol or the alpha-naphthol may be added to the emulsion. The film is washed and the treated emulsion is isolated by a thin layer of quickly dried gelatine, the two outer emulsion layers being coated on either side of the treated film. Development is by means 01 a solution made up as follows:-

For use, take equal parts or A and Band develop for 3% minutes at 18 C.

The color remains after the silver image is bleached out.

The two outer black silver images are converted into colored images by bleaching and any of the known methods of color toning or coloring referred to above.

It is to be understood that the three images are colored and toned respectively to the three subtractive colors complementary to the colors of the respective color separation records.

In any of the above examples the intermediate layer may, as shown in Figure 2 of the drawing, be isolated from the outer layer by a varnish, for example collodion, impermeable to water but permeable to a mixture of water with another liquid, for example alcohol. The outer layers may then be treated independently of the intermediate layer by reagents dissolved in water alone, whereas the intermediate layer may be treated by reagents dissolved in a mixture of water and alcohol.

In the above examples the intermediate layer may be colored any of the three subtractive colors, but it is preferred to color it minus blue, 1. e. a saturated yellow color.

It is desirable so to dispose the color sensitivity and the color of the printing lights that the outer layers are completely unafiected during the exposure of the intermediate layer. Thus the intermediate layer may be sensitized to the red, or infra red rays of the spectrum, but not to the green, whilst the two outer layers may be sensitized to the green and blue of the spectrum but not to the red. An exposing light containing only red rays will then be without efiect on the external emulsions, whilst a light containing only blue or green rays will only affect these outer emulsions. Alternatively, in the arrangements described in the examples, the intermediate layer may be sensitive to red rays only, and colored yellow, whilst the outer layers are specifically sensitized for the blue rays. All silver emulsions are sensitive to blue rays but by increasing this sensitivity by suitable dyes incorporated in the outer emulsions and by incorporating a yellow dyestufi in the intermediate emulsion, the exposure required to give developable images in the outer layers and given by blue light will be without effect on the intermediate layers. Alternatively, a water soluble dye may be added to the two outer emulsions, e. g. a yellow dye when printing by blue light. This method has the efiect of keeping the image on the surface of the emulsion, which is an advantage when the image is to be colored by the process described in British Specification No. 377,706.

According to an alternative method of printing the outer layers these two layers are sensitive to difierent portions of the spectrum and light of corresponding color is employed for printin these two layers. This method, however, sufiers from the disadvantage that the printing light must in practice be of low intensity and therefore considerable time is required for printing each of the layers.

If desired, two intermediate layers of emulsion may be employed, and these two layers may both contain a colored substance or color forming substance which may be the same in both layers or may be different. With this arrangement the layers may be two on each side of a transparent support, the inner layer on each side containing the colored substance or the color forming substance. When the two layers contain different color producing substances, one may conveniently be yellow and the other grey or black to form a key" image. This type of photographic material is illustrated by Figure 3 of the drawing.

It is an advantage of the present invention that the printing may be carried out from color separation negatives because in :those multilayer systems where printing is from separation positives, in that the eventual color image is dependent for its density on the coating weight of the emulsion, it is difficult to keep satisfactory color balance, since coating weights, particularly on the two-layer side, cannot be kept within the required limits under commercial conditions of manufacture.

Further, in those multi-layer systems where all three images are obtained from negatives and by the inclusion of color formers in the emulsion, the final color balance is determined when the emulsion is manufactured and the possibility of altering this to suit the requirements of the separation negatives or the scene is lost.

On the other hand, by using only one intermediate layer (or two) in which the strength of the color is fixed during coating, which color may be made the yellow for which the eye has greater tolerance when in excess, and using for the outer images the relief process already described, the opportunity is provided for adjusting balance by adjusting the pigment content of the applied gelatine layers. The two outer emulsions are of normal type and result in a cheaper film stock, and the advantages of relief images set out in British Specification No. 377,706 are here combined with a third color to give full three-color effect. The choice of suitable colors is less restricted when two of the colors are produced by the process of the above specification than is the case when all three are produced by means of color formers in the emulsions.

We claim:

l. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a support and at least three silver halide emulsion layers carried by said support, at least one of said layers being intermediate outer emulsion layers, said intermediate layers only containing a color .form-.

ing development component, said intermediate layers being sensitive to a spectral range diflerent from at least one of the outer layers.

2. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a single support and at least three superposed silver halide emulsion layers carried by said support including two outer layers, at least one side of said support having two of said layers, one of which is an intermediate layer between said support and an outer emulsion layer, said intermediate layers only containing a color forming development component and said intermediate layers being sensitive to a spectral range different from at least one of the outer layers.

3. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a single support and three superposed silver halide emulsion layers carried by said support including two outer layers, two of said layers being on one side of said support and the third on the other side thus material for use in the product of colored photographic records comprising a single support and four silver halide emulsion layers carried by said support with two of said layers on each side of saidsupport, thereby forming a photographic element having two exterior emulsion layers and two intermediate emulsion layers, said interme-.

diate layers only containing 'a colorforming de-,

velopment component and said intermediate.

layers being sensitive to a spectral range differ: ent from at least one of the exterior layers.

5. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a support and at least three, and not more than four super-- posed silver halide emulsion layers carried by said support including two outer layers, with two of said layers on one side of said support and at least one layer intermediate between said support and an outer emulsion layer, only intermediate layers containing a color forming development component, said intermediate layers being sensitive to a spectral range difierent from at least one of the outer layers.

6. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a support and a plurality of silver halide emulsion layers carried by said support including two outer layers with two layers on one side of said support and at least one layer on the other side of said support whereby the photographic material contains an emulsion layer intermediate between the support and an outer emulsion layer, said intermediate layer only containing a color forming development component, said component being that of a yellow dye and said intermediate layer being sensitive t o a spectral range diilferent from at least one of the outer layers. 1 l

7. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a single support and three silver halide emulsion layers carried by said support with two of said layers on one side of the support and one of said layers on the other whereby the photographic material contains an intermediate layer between the support and the outer emulsion layer, said intermediate layer only being red-sensitive and said intermediate layer only containing a color forming development component, said component being that of a yellow dye.

8. A light sensitive multi-layer photographic material for use in the production of colored photographic records comprising a support and four silver halide emulsion layers carried by said support with two of said layers on each side of said support whereby the photographic material contains two layers intermediate between the support and the outer emulsion layers, one of said intermediate layers containing a color formthe outer ing development component which develops yellow and the other of said intermediate layers containing a color formin development component which develops grey or black and is adapted to form a key image and the outer layers containing no color forming development components, said intermediate layers being sensitive to a spectral range difierent from at least one of the outer layers.

9. A light sensitive multi-layer photographi material for use in the production of colored photographic records comprising a support and at least three silver halide emulsion layers carried by said support, at least one of said layers being an intermediate layer which can be neither exposed. nor developed except by light passing through another emulsion layer, said intermediate layer only containing a color forming development component, said component comprising alpha naphthol.

10. The method of producing a colored photographic record which includes the steps of photographically printing a set of three color sepatively onto the three emulsion layers used during the printing of each layer with light filtering means so selected as to color and so located as to insure that substantially only that layer is eifected by the printing light, developing said photographic material with a developing agent adapted to form a color in said intermediate layer with the color forming development component and then treating the outer layers to form colored images appropriate to the color separation records which they represent.

11. The method of producing a colored photographic record which includes the steps of photographically printing a set of three color separation negatives onto light sensitive photographic material comprising two outer layers of photographic emulsion, an intermediate layer which can be neither exposed nor developed except by light passing through one of said outer layers, said intermediate layer only containing a color forming development component and said intermediate layer being red-sensitive, and at least one of said outer layers being blue-sensitive and not being red sensitive, the intermediate layer being printed with red light through said outer layer which is not red sensitive, developing said photographic material with a developing agent adapted to form a color in said intermediate layer and treating the outer layers to form colored images therein appropriate to the color separation records which they represent.

12. The method of producing a colored photographic record which includes the steps of photographically printing a set of three color separation records onto light sensitive photographic material comprising two outer layers of silver halide emulsion and an intermediate layer which can be neither exposed nor developed except by light passing through one of said outer layers, said intermediate layer only containing a color forming development component, and said intermediate. layer being sensitive to a different portion of the spectrum from that to which one of the outer layers is sensitive, the three records being printed respectively onto the three emulsion layers using an appropriate printlng light, developing said photographic material with an Eikonogen type developing agent adapted to form a color in the intermediate layer, and treating the outer layers to form colored images therein appropriate to the color separation records which they represent.

13. The method of producing a colored photographic record which includes the steps or photographically printing a set of three color separation records onto light sensitive photographic material comprising two outer layers of silver halide emulsion and an intermediate layer of silver halide emulsion, all of said layers being carried upon a single support, said intermediate layer only containing a color forming development component comprising alpha naphthol and said intermediate layer being red-sensitive and one of said outer layers not being red sensitive, the three records being printed respectively using the appropriate printing light, developing said photographic material with an Eikonogen type developing agent, and treating the outer layers to form colored images therein appropriate to the color separation records which they represent.

HUMPHREY DESMOND MURRAY. DOUGLAS ARTHUR SPENCER. 

